In the related art, vehicles have been known in which, when an internal pressure of a tubeless pneumatic tire is reduced in a new traffic system such as a monorail or a subway, a core-type auxiliary wheeled tire supporting the tubeless pneumatic tire from the inside is employed. As an example of the core of this pneumatic tire, a joint of the core split into three in a circumferential direction is adopted as a normal direction (a radial direction adopting an axle of the tire as a central axis), and each matching surface is fastened by a plurality of bolts and nuts (e.g., see Patent Document 1).
FIG. 15 shows an example of the core disclosed in Patent Document 1. The core 10 shown in FIG. 15 is provided with flange parts 10e, each of which has a bolt hole in a split surface of each of split pieces 10P obtained by splitting the core into three in a circumferential direction, and is configured so that the flange parts 10e of the adjacent split pieces 10P are coupled by a bolt and nut 10f. Thereby, the core 10 is formed in a ring shape.
Incidentally, in the core 10 as in FIG. 15, at normal times at which the tire 1 is not punctured, the core 10 is free of load in a state in which it is set in the tire, and there is a gap between a tire tread part and the core 10. When the tire 1 is punctured or when an internal pressure is reduced by air leakage, the tire becomes flat. In this case, the core 10 comes in contact with an inner surface of the tire tread part, and receives the load which the tire 1 covers. As a result, the core 10 rotates together with a wheel, restricts a lowering amount (or a sinking amount) caused by a puncture, and allows a vehicle to travel while suppressing inclination of the vehicle.